Valve seat apparatus having positive retention for use with fluid control devices

ABSTRACT

Valve seat apparatus having positive retention for use with fluid control devices are described herein. An example valve seat apparatus includes a metallic ring and an elastomeric ring coupled to the metallic ring and having a sealing surface to sealingly engage a flow control member of the fluid control device. At least a portion of an outer surface of the elastomeric ring includes an annular lip to sealingly engage an annular recess of a body of the fluid control device.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to fluid control devices and,more particularly, to valve seat apparatus having positive retention foruse with fluid control devices.

BACKGROUND

Fluid control devices, such as fluid regulators and control valves, arecommonly distributed throughout process control systems to control fluidflow rates and/or pressures of various fluids (e.g., liquids, gasses,etc.). For example, fluid regulators are typically used to regulate thepressure of a fluid to a lower and/or substantially constant value.Specifically, a fluid regulator has an inlet that typically receives asupply fluid at a relatively high pressure and provides a relativelylower and/or substantially constant pressure at an outlet. As the highpressure process fluid travels through the process control system, theregulator reduces the pressure of the process fluid at one or morepoints to supply a process fluid having a lower or reduced pressure to asub-system or other custody transfer points. For example, a regulatorassociated with a piece of equipment (e.g., a boiler) may receive afluid (e.g., gas) having a relatively high and somewhat variablepressure from a fluid distribution source and may regulate the fluid tohave a lower, substantially constant pressure suitable for safe,efficient use by the equipment.

A regulator typically reduces inlet pressure to a lower outlet pressureby restricting fluid flow through an orifice to match the fluctuatingdownstream demand. To restrict fluid flow between an inlet and anoutlet, a regulator typically employs a valve plug to engage a valveseat disposed within the orifice of the regulator body. Some known fluidregulators use a valve seat made from an elastomeric material to providea tight seal between the valve seat and a valve plug. In such knownregulators, the valve seat is typically disposed within the orifice sothat the frictional forces between the elastomeric valve seat and thebody of the regulator maintain the valve seat within the body of theregulator. However, this known frictional coupling of the valve seat tothe body of the regulator may allow the valve seat to shift or moverelative the body due to, for example, reverse pressure (i.e., backpressure) conditions, degradation of the elastomeric material, stickingbetween the valve plug and the valve seat (e.g., due to rubber bloom)when the valve plug moves away from the valve seat, etc. Such shiftingor movement of the valve seat relative to the body can causemisalignment between the valve seat and the valve plug, thereby causingunwanted leakage of fluid past the valve seat and affecting theperformance of the fluid regulator.

SUMMARY

In one example, a valve seat apparatus having a positive retention foruse with a fluid control device includes a metallic ring and anelastomeric ring coupled to the metallic ring and having a sealingsurface to sealingly engage a flow control member of the fluid controldevice. At least a portion of an outer surface of the elastomeric ringincludes an annular lip to sealingly engage an annular recess of a bodyof the fluid control device.

In another example, a valve seat apparatus having a positive retentionfor use with a fluid regulator includes a substantially rigid supportmember coupled to a substantially resilient sealing member. An innersurface of the sealing member is coupled to the outer surface of thesupport member and at least a portion of an outer surface of the sealingmember has a first outer diameter and a second outer diameter largerthan the first outer diameter to form at least one protruding member toretain the valve seat apparatus in a body of the fluid regulator.

In yet another example, a fluid regulator includes a body having ashoulder formed by an annular cavity in the body between an inlet and anoutlet and a valve seat disposed within the body. The valve seatincludes a first ring-shaped member and a second ring-shaped membercoupled to the first ring-shaped member to provide a sealing surface tosealingly engage a movable valve plug of the regulator. The secondring-shaped member has an outer lip portion frictionally engaged in theannular cavity so that the lip portion engages the shoulder of the bodyto retain the valve seat in the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of a fluid regulatorimplemented with an example valve seat apparatus described herein.

FIG. 2A is a more detailed view of the example valve seat apparatusillustrated in FIG. 1.

FIG. 2B is another detailed view of the example valve seat apparatusillustrated in FIG. 2A.

FIG. 3A is an enlarged partial cutaway view of the example valve seatapparatus and the fluid regulator of FIGS. 1, 2A, and 2B.

FIG. 3B is an enlarged partial cutaway view of the example valve seatapparatus and fluid regulator of FIGS. 1, 2A, 2B, and 3A.

DETAILED DESCRIPTION

In general, fluid regulators modulate the flow of fluid in accordancewith a sensed downstream pressure to maintain process system pressureswithin acceptable and/or constant pressure limits. Fluid regulatorstypically regulate the flow and pressure of process fluid in response toa difference between an outlet fluid pressure (i.e., a force applied toone side of a diaphragm) and a pre-set control force (i.e., a forceapplied to another side of the diaphragm) to vary the flow through theregulator to achieve a substantially constant outlet pressure.

Fluid regulators typically include a diaphragm operatively coupled to avalve plug via a diaphragm plate and a valve stem. The diaphragm movesin a rectilinear path in response to a difference in force between aforce exerted by the pressure of the fluid at the outlet and a pre-setforce (e.g., set via a spring). Movement of the diaphragm causes thevalve plug to move away from or toward a valve seat to allow or restrictthe flow of fluid between the inlet and the outlet of the regulator. Insome known regulators, the valve seat is made of an elastomeric materialand is frictionally coupled to the body of the regulator. In particular,frictional forces between the elastomeric material of the valve seat andan inner surface the regulator body hold the valve seat in positionrelative to the regulator body. However, this known configuration mayallow the valve seat to shift or move relative to the body due to, forexample, reverse pressure conditions (i.e., back pressure conditions)that occur when the outlet pressure is substantially greater than theinlet pressure (e.g., when the valve plug is away from the valve seat).Such back pressure conditions may be due to, for example, temperaturefluctuations of the fluid. Additionally or alternatively, degradation ofthe elastomeric material of the valve seat may allow the valve seat toshift or move relative to the valve body. Additionally or alternatively,when the valve plug engages the valve seat for an extended period oftime, the elastomeric valve seat may stick or attach to an edge of avalve plug due to, for example, compounds in the elastomeric materialleaching out and attaching to the valve plug (e.g., rubber bloom),thereby causing the valve seat to move or shift relative to the body ofthe regulator when the valve plug moves away from the valve seat. Suchshifting or movement of the valve seat relative to the body can causemisalignment between the valve seat and the valve plug, thereby causingunwanted leakage past the valve seat and affecting the performance ofthe fluid regulator.

The example valve seat apparatus described herein provide a positiveretention to substantially prevent movement of the valve seat apparatusrelative to a body of a fluid control device such as, for example, afluid regulator. In one example described herein, a valve seat apparatusis coupled (e.g., frictionally coupled, fixedly coupled, etc.) to aregulator body to prevent inadvertent back out of the valve seatapparatus during valve operation. In particular, an example valve seatapparatus described herein includes an elastomeric ring thatfrictionally engages or fits within an orifice of a regulator body (orother fluid control device body) to frictionally couple the valve seatapparatus to the regulator body. The elastomeric ring is coupled to ametallic ring, which provides rigid support to the resilient elastomericring. Additionally, unlike known valve seats, the example elastomericring includes an annular lip that frictionally engages (e.g., isdisposed within) an annular cavity or groove of the regulator bodyadjacent the orifice of the regulator body. Also, the annular lip formsa shoulder that engages a shoulder of the body formed by the annularcavity or groove. In this manner, the engagement of the lip with thecavity and the shoulder of the body provides a positive retention andsubstantially prevents movement of the valve seat apparatus relative tothe regulator body. Such positive retention is particularly advantageousin applications that experience reverse back pressures between the inletand the outlet (i.e., outlet pressures that exceed inlet pressures),sticking between the valve plug and the valve seat (e.g., due to rubberbloom) when the valve plug moves away from the valve seat after thevalve plug engages the valve seat for an extended period of time, etc.,by preventing movement of the valve seat apparatus relative to the body.

FIG. 1 illustrates a cross-sectional view of an example fluid regulator100 implemented with an example valve seat apparatus 102 describedherein. In this example, the fluid regulator 100 includes an upper body104 and a lower body 106 that are coupled together via a plurality offasteners 108. A diaphragm 110 is captured between the upper body 104and the lower body 106. The upper body 104 and a first side 112 of thediaphragm 110 define a first chamber 114. A spring 116 is disposedwithin the upper body 104 between a first spring seat 118 and anadjustable second spring seat 120. In this example, the first chamber114 is fluidly coupled to, for example, the atmosphere, via an aperture122.

The first spring seat 118 is coupled to a diaphragm plate 124 thatsupports the diaphragm 110. A spring adjuster 126 (e.g., a screw)engages the second spring seat 120 to enable adjustment of the length ofthe spring 116 (e.g., compress or decompress the spring 116) and, thus,adjustment (e.g., to increase or decrease) of the amount of a pre-setforce or load that the spring 116 exerts on the first side 112 of thediaphragm 110.

The lower body 106 and a second side 128 of the diaphragm 110 at leastpartially define a second chamber 130, an inlet 132, and an outlet 134.The second chamber 130 is fluidly coupled to the outlet 134 via achannel 136. The valve seat apparatus 102 is disposed within the lowerbody 106 and defines an orifice 138 between the inlet 132 and the outlet134. A valve plug 140 is operatively coupled to the diaphragm 110 via avalve stem 142 and the diaphragm plate 124. A second spring 144 isdisposed within a cavity 146 of a valve plug retainer 148 to bias thevalve plug 140 toward the valve seat apparatus 102. In the illustratedexample, the valve plug 140 engages the valve seat apparatus 102 toprovide a tight seal to prevent fluid flow between the inlet 132 and theoutlet 134. The spring rate of the second spring 144 is typicallysubstantially smaller relative to the spring rate of the spring 116.

In this example, the fluid regulator 100 includes an internal reliefvalve 150 coupled to the diaphragm 110 via the diaphragm plate 124. Therelief valve 150 includes an aperture 152 that fluidly couples the firstchamber 114 and the second chamber 130. A second end 154 of the valvestem 142 includes a soft or compliant seat 156 that engages the aperture152 of the relief valve 150 to prevent (e.g., block) the flow of fluidbetween the first and second chambers 114 and 130, respectively.However, in other examples, the fluid regulator 100 may include acoupling seat (i.e., a non-venting seat) instead of the internal reliefvalve 150 to operatively couple the diaphragm 110 and the valve plug140. In yet other examples, the valve stem 142 may be fixedly coupled tothe diaphragm plate 124 (e.g., via fasteners).

In operation, the inlet 132 is in fluid communication with, for example,an upstream fluid distribution source that provides fluid having arelatively high pressure. The outlet 134 is in fluid communication witha downstream demand source, pressure regulator, or any other custodypoint that demands process fluid at a desired (e.g., a lower) pressure.

The fluid regulator 100 typically regulates the upstream pressure of thefluid at the inlet 132 to provide or develop a desired pressure at theoutlet 134. To achieve a desired outlet pressure, the spring 116 exertsa force on the first side 112 of the diaphragm 110 which, in turn,positions the valve plug 140 relative to the valve seat apparatus 102 torestrict the flow of the process fluid between the inlet 132 and theoutlet 134. Thus, the outlet or desired pressure is dependent upon theamount of pre-set force exerted by the spring 116 to position thediaphragm 110 and, thus, the valve plug 140 relative to the valve seatapparatus 102. The desired pressure set point may be configured byadjusting the force exerted by the spring 116 on the first side 112 ofthe diaphragm 110 via the spring adjuster 126.

When the downstream demand increases, the pressure of the fluid at theoutlet 134 decreases. The second chamber 130 senses the decreasingpressure of the process fluid at the outlet 134 via the channel 136.When the force exerted on the second side 128 of the diaphragm 110 bythe pressure of the fluid in the second chamber 130 decreases below thepre-set force exerted by the spring 116 on the first side 112 of thediaphragm 110, the spring 116 causes the diaphragm 110 to move towardthe second chamber 130. When the diaphragm 110 moves toward the secondchamber 130, the valve plug 140 moves away from the valve seat apparatus102 to allow fluid to flow through the orifice 138 between the inlet 132and the outlet 134 (e.g., an open position), thereby causing thepressure at the outlet 134 to increase.

Conversely, as the outlet or downstream demand decreases or is shut-off,the pressure of the process fluid at the outlet 134 increases. As notedabove, the increasing fluid pressure at the outlet 134 is registered inthe second chamber 130 via the channel 136 and exerts a force on thesecond side 128 of the diaphragm 110. When the pressure of the fluid inthe second chamber 130 exerts a force on the second side 128 of thediaphragm 110 that equals or exceeds the pre-set force exerted by thespring 116 on the first side 112 of the diaphragm 110, the diaphragm 110moves toward the first chamber 114 (e.g., an upward direction againstthe force exerted by the spring 116 in the orientation of FIG. 1). Whenthe diaphragm 110 moves toward the first chamber 114, the diaphragm 110causes the valve plug 140 to move toward the valve seat apparatus 102 torestrict the flow of fluid through the orifice 138. The second spring144 biases the valve plug 140 toward the valve seat apparatus 102 tosealingly engage the valve seat apparatus 102 (e.g., in a closedposition) to substantially prevent fluid flow through the orifice 138between the inlet 132 and the outlet 134 and, thus, reduce supply of thepressure to the downstream source (i.e., a lock-up condition). A lock-upcondition of the fluid regulator 100 occurs when the valve plug 140sealingly engages the valve seat apparatus 102 to provide a tight sealand prevent fluid flow between the inlet 132 and the outlet 134.

During normal operation (e.g., prior to lock-up), the soft seat 156engages the aperture 152 of the relief valve 150 to prevent unwantedleakage of fluid between the first and second chambers 114 and 130. Atthe onset of the lock-up condition, the valve plug 140 engages the valveseat apparatus 102 to prevent the flow of fluid between the inlet 132and the outlet 134.

However, in some instances, the pressure of the fluid at the outlet 134increases when the downstream demand decreases (e.g., the downstreamsource is shut-off) and the valve plug 140 fails to sealingly engage thevalve seat apparatus 102 (i.e., the regulator 100 fails to lock-up) dueto, for example, grit, pipe scale, etc. The increase in pressure of thefluid at the outlet 134 exerts a force on the second side 128 of thediaphragm 110 that causes the diaphragm 110 and the diaphragm plate 124to move toward the first chamber 114 (i.e., to compress the spring 116in an upward direction in the orientation of FIG. 1). As a result, therelief valve 150, which is coupled to the diaphragm 110 via thediaphragm plate 124, moves away from the soft seat 156. Movement of thediaphragm 110 toward the first chamber 114 causes the internal reliefvalve 150 to move away from the soft seat 156 to fluidly couple thesecond chamber 130 and the first chamber 114 to bleed or vent thepressure to, for example, the atmosphere via the aperture 122.

The example valve seat apparatus 102 described herein advantageouslyprevents the valve seat apparatus 102 from inadvertently backing out ofthe lower body 106 (i.e., moving away from the body 106) due to backpressure conditions. Unlike some known valve seats, for example, anoutlet pressure that is greater than the inlet pressure does not causethe valve seat apparatus 102 to shift or move relative to the lower body106 (e.g., the orifice 138). Additionally or alternatively, the exampleseat apparatus 102 described herein advantageously prevents the valveseat apparatus 102 from inadvertently shifting or moving relative to thelower body 106 due to, for example, the valve plug 140 sticking orattaching to the valve seat apparatus 102 (e.g., due to rubber bloom)when the valve plug 140 moves away from the valve seat apparatus 102after the valve plug 140 engages the valve seat apparatus 102 for anextended period of time. As noted above, preventing such movementprevents misalignment between the valve plug 140 and the valve seatapparatus 102, thereby improving regulator performance.

FIG. 2A is a more detailed view of the example valve seat apparatus 102illustrated in FIG. 1. FIG. 2B is another detailed view of the examplevalve seat apparatus 102 illustrated in FIG. 2A. Referring to FIGS. 2Aand 2B, the example valve seat apparatus 102 includes a sealing member202 coupled to a rigid support member 204. In this example, the sealingmember 202 is a substantially resilient elastomeric ring-shaped memberor ring and the rigid support member 204 is a substantially rigidmetallic ring-shaped member or ring. The elastomeric ring 202 is coupledto the metallic ring 204 and provides sealing surfaces 206 and 208.

In this example, at least a portion of the elastomeric ring 202 includesat least one protruding member or annular lip 210. The elastomeric ring202 has a first outer diameter 212 and a second outer diameter 214 thatis larger than the first outer diameter 212 to form the lip 210. The lip210 also forms a shoulder 216 between the diameters 212 and 214.Although not shown, in other examples, the elastomeric ring 202 mayinclude a plurality of annular lips. The elastomeric ring 202 may bemade of, for example, rubber, nitrile, fluoroelastomer (FKM), Neoprene,or any other suitable elastomeric and/or resilient materials.

The elastomeric ring 202 surrounds the metallic ring 204 so that themetallic ring 204 supports the elastomeric ring 202. The metallic ring204 has an aperture 218 that provides a fluid flow passageway when thevalve seat apparatus 102 is disposed within the lower body 106 of thefluid regulator 100. In this example, the metallic ring 204 is made ofstainless steel and manufactured via machining. However, in otherexamples, the ring 204 may be made of brass, carbon steel, plastic, orany other suitable rigid material(s). In yet other examples, themetallic ring 204 may be manufactured via molding and/or any othersuitable manufacturing process(es).

In this example, the elastomeric ring 202 is coupled to the metallicring 204 via molding (e.g., over molding). The elastomeric ring 202 ismolded over the metallic ring 204 to form the valve seat apparatus 102.In other examples, the elastomeric ring 202 may be assembled or pressfit to the metallic ring 204 to form the valve seat apparatus 102. Tofacilitate coupling the elastomeric ring 202 to the metallic ring 204via, for example, molding, the metallic ring 204 includes an annularprotruding edge 302 (FIG. 3B) protruding from an outer surface 304 (FIG.3B) of the metallic ring 204. The protruding edge 302 may be formed via,for example, machining. In this example, the protruding edge 302 has arectangular cross-sectional shape. However, in other examples, theprotruding edge 302 may have a T-shape cross-sectional shape, an arcuatecross-sectional shape, or any other suitable cross-sectional shape.Likewise, an inner surface 306 (FIG. 3B) of the elastomeric ring 202 has(e.g., forms) an annular groove 308 to receive the protruding edge 302when the elastomeric ring 202 is coupled (e.g., over molded) to themetallic ring 204. In other examples, the elastomeric ring 202 may becoupled or bonded to the metallic ring 204 via chemical fasteners (e.g.,adhesives) or any other suitable fastening mechanism(s). In thisexample, a portion 307 of the outer surface 304 of the metallic ring 204is tapered. In other examples, the outer surface 304 of the metallicring 204 may include any other suitable shape.

FIG. 3A illustrates an enlarged partial cutaway view of the examplevalve seat apparatus 102 and the fluid regulator 100 of FIGS. 1, 2A, and2B. FIG. 3B illustrates an enlarged partial cutaway view of the examplevalve seat apparatus 102 and fluid regulator 100 shown in FIGS. 1, 2A,2B, and 3A. Referring to FIGS. 3A and 3B, the valve seat apparatus 102is disposed within (e.g., inserted into) the lower body 106 of the fluidregulator 100 to encompass a flow path between the inlet 132 and theoutlet 134. More specifically, the valve seat apparatus 102 isfrictionally fit or coupled to the orifice 138 of the lower body 106.The lower body 106 includes an undercut or cavity 310 that forms ashoulder 312. The valve seat apparatus 102 is press fit within theorifice 138 (e.g., via a tool) so that the lip 210 engages (e.g., isinserted into) the cavity 310 of the lower body 106. In this manner, thelip 210 is disposed within the cavity 310 so that the shoulder 216 ofthe elastomeric ring 202 engages the shoulder 312 of the lower body 106.As a result, the valve seat apparatus 102 provides a positive retentionto prevent the valve seat apparatus 102 from moving or shifting relativeto the lower body 106. The shoulder 312 may have a tapered edge, asubstantially right-angled edge, a chamfered edge, or any other suitableedge.

Additionally, the frictional forces between the sealing surface 208 andthe lip 210 of the elastomeric ring 202 and respective surfaces 314 and316 of the lower body 106 frictionally couple the valve seat apparatus102 to the lower body 106 when the valve seat apparatus 102 is disposedwithin the lower body 106. The metallic ring 204 provides support to theelastomeric ring 202 and exerts radial reactive forces in a directiontoward the surfaces 314 and 316 of the lower body 106 to prevent theelastomeric ring 202 from radially collapsing (e.g., folding) toward theorifice 138 when disposed within the lower body 106. As most clearlyshown in FIG. 3B, the lip 210 is compressed between the surface 314 andthe outer surface 304 of the metallic ring 204 when disposed in thecavity 310 of the lower body 106. Similarly, the sealing surface 208 iscompressed between the surface 316 of the lower body 106 and the outersurface 304 of the metallic ring 204.

In operation, the valve plug 140 sealingly engages the sealing surface206 of the elastomeric ring 202 to prevent fluid flow between the inlet132 and the outlet 134. In this example, the valve plug 140 has aknife-edge cross-sectional shape 318 that engages the sealing surface206. However, in other examples, the valve plug 140 may have any othersuitable cross-sectional shape. When the valve plug 140 moves away fromthe sealing surface 206, fluid flows between the inlet 132 and theoutlet 134 through the aperture 218 of the metallic ring 204. If thevalve seat apparatus 102 is exposed to high pressures and/or backpressure conditions, the lip 210 provides a positive retention andprevents the valve seat apparatus 102 from moving or shifting relativeto the lower body 106, thereby improving regulator performance.

Additionally or alternatively, in operation, the lip 210 provides apositive retention to prevent the valve seat apparatus 102 from movingrelative to the valve plug 140 if the valve plug 140 sticks or attachesto the sealing surface 206. For example, in operation, the valve plug140 may engage the sealing surface 206 of the valve seat apparatus 102for a substantial period of time (e.g., during a lock-up condition ofthe regulator 100). As a result, the knife-edge 318 of the valve plug140 may stick or attach to the sealing surface 206 due to, for example,compounds of the elastomeric ring 202 leaching thereby causing the valveplug 140 to attach to the sealing surface 206 (e.g., due to rubberbloom). When the valve plug 140 moves away from the valve seat apparatus102 to the open position, the lip 210 provides a positive retention andprevents the valve seat apparatus 102 from moving or shifting relativeto the lower body 106.

The example valve seat apparatus 102 is not limited for use with theexample fluid regulator 100 of FIGS. 1, 2A, 2B, 3A, and 3B. In otherexamples, the valve seat apparatus 102 may be implemented with otherfluid regulators, control valves (e.g., linear valves, rotary valves,etc.), and/or any other suitable fluid control devices.

Although certain example apparatus have been described herein, the scopeof coverage of this patent is not limited thereto. On the contrary, thispatent covers all apparatus and articles of manufacture fairly fallingwithin the scope of the appended claims either literally or under thedoctrine of equivalents.

What is claimed is:
 1. A fluid control device, comprising: a valve bodycomprising an aperture, the aperture having a shoulder defining a firstgroove of the valve body and a first angled surface between the shoulderand an end of the aperture; and a valve seat comprising a positiveretention for use with the fluid control device, the valve seatcomprising: a metallic ring comprising a first inner circumferentialsurface and a first outer circumferential surface, the first outercircumferential surface comprising a first protrusion and a secondangled surface, the first and second angled surfaces being non-paralleland non-perpendicular relative to an axis extending through the valveseat; and an elastomeric ring comprising a sealing surface, a secondinner circumferential surface, and a second outer inner circumferentialsurface, the second inner circumferential surface comprising a secondgroove and a third angled surface, the second outer circumferentialsurface comprising a second protrusion and a fourth angled surface, thethird and fourth angled surfaces being non-parallel andnon-perpendicular relative to the axis extending through the valve seat,the sealing surface to be sealingly engaged by a flow control member ofthe fluid control device, the metallic ring being attached to theelastomeric ring prior to positioning the metallic ring and theelastomeric ring in the valve body of the fluid control device, thethird angled surface of the elastomeric ring to matably engage thesecond angled surface of the metallic ring, the metallic ring disposedin an opening of the elastomeric ring and configured so that themetallic ring is not to engage the flow control member, the sealingsurface to be positioned between the metallic ring and the valve body ofthe fluid control device prior to engagement of the flow control memberwith the sealing surface and during engagement of the flow controlmember with the sealing surface, the metallic ring to exert a radialforce to the elastomeric ring to urge the first protrusion into thesecond groove, the second protrusion into the first groove, and thefourth angled surface to matably engage the first angled surface.
 2. Afluid control device as defined in claim 1, wherein the elastomeric ringis frictionally coupled to the valve body of the fluid control device.3. A fluid control device as defined in claim 1, wherein a surface ofthe metallic ring opposite the sealing surface of the elastomeric ringengages a surface of the valve body defined by the first groove.
 4. Afluid control device as defined in claim 1, wherein the first groove ofthe elastomeric ring is disposed at approximately a midpoint of thefirst inner circumferential surface of the elastomeric ring between afirst edge of the elastomeric ring and a second edge opposite the firstedge.
 5. A fluid control device as defined in claim 1, wherein the valveseat is retained within the valve body without the use of a cage.
 6. Afluid control device as defined in claim 1, wherein upper and loweredges of the metallic ring are substantially aligned with respectiveupper and lower edges of the elastomeric ring when the metallic ring iscoupled to the elastomeric ring.
 7. A fluid control device as defined inclaim 1, wherein a first edge of the metallic ring is substantiallyflush relative to a first edge of the sealing surface of the elastomericring.
 8. A fluid control device as defined in claim 7, wherein a secondedge of the metallic ring is substantially flush relative to a secondedge of the elastomeric ring opposite the sealing surface.
 9. A fluidcontrol device as defined in claim 1, wherein the first protrusion ispositioned between an upper edge and a lower edge of the metallic ring.10. A fluid control device as defined in claim 1, wherein the end of theaperture comprises a curved surface.
 11. A fluid control device asdefined in claim 10, further comprising a chamfered portion adjacent thesecond outer circumferential surface and opposite the sealing surface,the chamfered portion to slidably engage the curved surface of the endto facilitate the second protrusion of the elastomeric ring beingreceived by the first groove of the valve body.
 12. A valve seatapparatus having a positive retention for use with a fluid regulator,comprising: a substantially rigid support ring coupled to asubstantially resilient sealing ring, the rigid support ring comprisinga first inner surface and a first outer surface, the first outer surfacecomprising a first protrusion, the resilient sealing ring comprising asecond inner surface, a second outer surface, and a sealing surface, thesecond inner surface comprising a first recess, the second outer surfacecomprising a second protrusion and a chamfered portion, the chamferedportion adjacent the second outer surface and opposite the sealingsurface, the sealing surface to be engaged by a valve plug of the fluidregulator, the sealing surface being substantially flush with an edge ofthe rigid support ring when the rigid support ring and the resilientsealing ring are positioned in a valve body of the fluid regulator, thefirst recess to receive the first protrusion to couple the rigid supportring and the resilient sealing ring, the chamfered portion to slidablyengage a curved portion adjacent an opening of the valve body tofacilitate the second protrusion being received within a second recessof the valve body, when the valve seat apparatus is positioned withinthe valve body, the rigid support ring to exert an outward radial forceto the resilient sealing ring to urge the first protrusion into thefirst recess and the second protrusion into the second recess, whereinthe second outer surface comprises a first angled surface non-paralleland non-perpendicular relative to an axis extending through the valveseat apparatus when the valve seat apparatus is positioned in the valvebody, the first angled surface to matably engage a second angled surfaceof the valve body when the rigid support ring and the resilient sealingring are positioned in the valve body.
 13. A valve seat apparatus asdefined in claim 12, wherein the second protrusion is to be press fitinto the second recess of the valve body of the fluid regulator.
 14. Avalve seat apparatus as defined in claim 12, wherein the resilientsealing ring substantially surrounds the rigid support ring.
 15. A valveseat apparatus as defined in claim 12, wherein the rigid support ringcomprises a metallic ring and the resilient sealing ring comprises anelastomeric ring.
 16. A valve seat apparatus as defined in claim 12,wherein the first recess in the resilient sealing ring is disposedadjacent a midpoint of the resilient sealing ring between a first edgeof the resilient sealing ring and a second edge of the resilient sealingring opposite the first edge.
 17. A valve seat apparatus as defined inclaim 12, wherein a height of the rigid support ring along an axisextending through the valve seat apparatus is substantially equal to aheight of the resilient sealing ring along the axis extending throughthe valve seat apparatus.
 18. A valve seat apparatus as defined in claim12, wherein the second protrusion forms a first lip to directly engage asecond lip formed by the second recess of the valve body of the fluidregulator.
 19. A valve seat apparatus as defined in claim 12, whereinthe first outer surface comprises a third angled surface and the secondinner surface comprises a fourth angled surface matably engaged to thethird angled surface, the third and fourth angled surfaces beingnon-parallel and non-perpendicular relative to an axis extending throughthe valve seat apparatus.
 20. A fluid regulator, comprising: a valvebody comprising an inlet, an outlet, an aperture positioned between theinlet and the outlet, and a curved portion adjacent an opening of theaperture, the aperture comprising a shoulder to define a first groove;and a valve seat disposed within the aperture of the valve body, thevalve seat comprising: a first ring-shaped portion comprising a firstinner surface and a first outer surface, the first outer surfacecomprising a first protrusion; and a second ring-shaped portion thatsurrounds the first ring-shaped portion to be sealingly engaged by amovable valve plug, the second ring-shaped portion comprising a secondinner surface, a second outer surface, a sealing surface, and achamfered portion, the second outer surface comprising a secondprotrusion to engage the shoulder and to be received by the first grooveto retain the valve seat relative to the valve body, the chamferedportion to slidably engage the curved portion adjacent the opening ofthe aperture to facilitate positioning the first and second ring-shapedportions within the valve body, the second inner surface comprising asecond groove to receive the first protrusion of the first ring-shapedportion, the first ring-shaped portion being disposed in an opening ofthe second ring-shaped portion, the sealing surface to be sealinglyengaged by the movable valve plug when the valve seat is retainedrelative to the valve body, the first ring-shaped portion to exert aradial outward force to the second ring-shaped portion to urge the firstprotrusion into the second groove and the second protrusion into thefirst groove, the second outer surface further comprises a first angledsurface and the valve body comprises a second angled surface, the firstand second angled surfaces being non-parallel and non-perpendicularrelative to an axis extending through the valve seat, the first andsecond angled surfaces to matably engage when the valve seat is retainedrelative to the valve body.
 21. A fluid regulator as defined in claim20, wherein the first ring-shaped portion comprises a metallic ring andthe second ring-shaped portion comprises an elastomeric ring.
 22. Afluid regulator as defined in claim 20, wherein a surface of the firstring-shaped portion opposite the sealing surface frictionally engagesthe shoulder of the valve body to retain the valve seat in the valvebody.
 23. A fluid regulator as defined in claim 20, wherein the sealingsurface is positioned between the first ring-shaped portion and thevalve body of the fluid regulator prior to the sealing surface beingengaged with the movable valve plug and during engagement of the movablevalve plug with the sealing surface.
 24. A fluid regulator as defined inclaim 20, wherein the first outer surface comprises a third angledsurface and the second inner surface comprises a fourth angled surfacethat is to matably engage to the third angled surface, the third andfourth angled surfaces being non-parallel and non-perpendicular relativeto an axis extending through the valve seat.